Improved tool for grinding annular valve seats



Oct. 18, 1960 M. YULE 2,956,380

IMPROVED TOOL FOR GRINDING ANNULAR VALVE SEATS Filed March 5, 1957 7.1 p i i; i

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4' /0 H g I I} H I g I! g (/0 I I {I I i {I 1 J @Q O (B 1 62 27 i 33 i i Inventor:

B 3;, i JWM] M Attorneys.

United States Patent IMPROVED TOOL FOR GRINDING ANNULAR VALVE SEATS Ian Munro Yule, 145 Yarningale Road, Kings Heath. Birmingham, England Filed Mar. 5, 1957, Ser. No. 644,034

4 Claims. (Cl. 51241) This invention relates to an improved tool for grinding annular valve seats.

One object of the invention is to provide an improved grinding tool which operates on the eccentric grinding principle, whereby when the tool is set up for operation on a valve seat, the axis of rotation of the grinding wheel is offset in relation to the axis of the seat, so that the wheel which is traversed round the seat makes line contact with the seat surface which is being ground.

A further object of the invention is to provide improved means for locating a grinding tool Working on an annular valve seat which has an axially disposed guide, in which a pilot shaft on the tool can engage.

The invention is illustrated in its various forms in the accompanying drawings which depict a tool for grinding annular valve seats and wherein:

Figure 1 is a side elevation of the tool.

Figure 2 is a section on the line 22 in Figure 1.

Figure 3 is a section on the line 3-3 in Figure 2.

The grinding tool shown in the accompanying drawings has a main outer body portion which is of hollow cylindrical form with a reduced cylindrical portion 11 at the lower end thereof and at the top there is provided a finger grip member 12 having a circular flange 13 by means of which it is secured to the upper end of the body 10 using screws 14.

. Within the body 10 there is an electric motor indicated diagrammatically at 15 to the armature of which is secured the grinding wheel shaft 17 extending coaxially within the main body 10 and reduced portion of the main body 11.

The upper end of the armature shaft at 18 has at its top a ball thrust bearing 19, below which is arranged a coiled compression spring 20 which serves to urge the armature and grinding wheel shaft 17 upwardly to press the thrust bearing 19 against the underside of an adjustment cap 21, which is secured to the member 12 by means of a screw 22, the periphery 23 of the cap 21 being knurled so that it can be turned easily for the purpose of moving the grinding wheel shaft axially relative to the body 10 so that the grinding wheel 24 which is carried at the lower end of the shaft 17 can be adjusted for degree of cut relative to the valve seat which is being ground.

A spring pressed ball 25 acts as a non-positive lock for retaining the cap 21 in any desired adjusted position.

Projecting endwise from the reduced portion of the body is an externally threaded sleeve 26, this sleeve 26 being rotatable in the reduced portion 11 and the bore of the sleeve 26 is suitably lined to provide a bearing for this end of the shaft 17.

A locating sleeve has a main body portion 28 which is of cylindrical form and a frustro-conical portion 29 which engages the valve seat which is being ground and at the apex of this portion 29, there is a boss 30 within which is detachably secured by grub screw 31, a pilot shaft 32 which is adapted to engage in the guide associated with the valve seat which is being ground.

The locating sleeve is formed at its upper end 33 with an opening of circular form which is eccentrically disposed in relation to the axis of the locating sleeve and pilot shaft 32, this circular opening being internally threaded so that it can be screwed upon the externally threaded sleeve 26, in which position, as will be seen in Figure 2, the axis of the pilot shaft 32 is offset from the axis of the grinding tool shaft 17. The locating sleeve is positioned on the externally threaded sleeve 26 by means of the internally threaded locking collar 27.

The bowed spring washer 61 acts to urge the sleeve 26 upwardly so that the flange 62 is thrust against the shoulder 63 on the interior of the reduced body portion 11. A thrust washer or rotary thrust race may be provided at this position.

The locating sleeve is formed with an opening 34 which extends over the cylindrical portion 28 and the frustro-conical portion 29 and it will be observed that the periphery of the operative surface of the grinding wheel 24 is positioned in this opening 34 so that when the locating sleeve is engaging a valve seat with its frustro-conical portion 29, the operative surface of the grinding wheel is also in engagement with the valve seat. The sleeve 29 locates the grinding wheel axially and in combination with the pilot shaft also locates the grinding wheel in the radial direction.

Hence when the locating sleeve is driven at a reduced speed from the electric motor 15 through reduction gear ing, the axis 17 of the grinding wheel is caused to traverse in a circular path about the axis of the pilot shaft 32, thus traversing the grinding wheel 24 around the valve seat and performing a grinding operation on the eccentric grinding principle.

It will be observed that the grinding wheel, locating sleeve and pilot shaft are also detachable, so as to be capable of being exchanged for corresponding members of different sizes for dealing with various seats of different dimensions.

The grinding wheel shaft 17 would be rotated at a speed of about 10,000 r.p.m. and the desired speed of rotational traverse of the locating sleeve would be about 20 r.p.m. so that a reduction gearing of 500 to l is required.

What I claim then is:

1. A tool for grinding an annular valve seat having a fnlstro-conical portion and an axially aligned guide, said tool comprising, an outer body, a spindle rotatably mounted within said outer body, a generally cylindrical locating sleeve supported from said outer body, a grinding wheel mounted on one end of said spindle and within said locating sleeve, a pilot shaft fixed to the free end of said locating sleeve and co-axial therewith for engaging in the guide of the valve seat, the axis of the grinding wheel spindle being off-set from the common axis of the locating sleeve and pilot shaft, said locating sleeve having, adjacent the free end thereof, an externally frustro-conical portion for engaging in the frustro-conical portion of the valve seat and also having an opening interrupting said frustroconical portion and extending for less than half the circumference of said frustro'conical portion, and the grinding wheel being positioned within said locating sleeve so as to have a portion of its operative grinding surface project ng through said opening.

2. A tool for grinding an annular valve seat having a frustro-conical portion and an axially aligned guide, said tool comprising an outer body of generally hollow cylindiical formation, a sleeve member mounted for rotation co-axially within the outer body and having a free end projecting beyond an end of the outer body, a spindle rotatably mounted co-axially within said sleeve member and having one end projecting beyond the said free end of the sleeve member, the said free end of the sleeve member having an external screwthread, a gene-rally cylindrical locating sleeve mounted upon said free end of the sleeve member and having an internal-screwthread which engages the external screwthread on the sleeve member, a grinding Wheel mounted on the projecting end of said spindle and Within said locating sleeve, a pilot shaft fixed to the free end of said locatingsleeve and co-axial therewith for engaging in the guide of the valve seat, the axis of the grinding wheel spindle being offset from the common axis of the locating sleeve and pilot shaft, said locating sleeve having, adjacent the free end thereof, an externally frustro-conical portion forengaging in the frustro-conical portion of the valve seat and also having an opening interrupting said frustroconical portion and extending for less than half the circumference of said frustro-conical portion, and the grinding wheelzbeing positioned within saidrlocating sleeve so as to have a portion of its operative grinding surface projecting through said opening.

3. A tool for grinding an annular valve seat having a frustro-conical portion and an axially aligned guide, said tool comprising, an outer body, of generally hollow cylindrical formation, a sleeve member mounted for rotation co-axially within the outer body and having a free end projecting beyond an end of the outer body, a spindle rotatably mounted co-axially within said sleeve member and having one end projecting beyond the said free end of the sleeve member, a driving motor mounted Within said outer body and directly connected to said spindle, reduction gearing housed within the outer body and operatively connected between said driving motor and said sleeve member to rotate the latter at a slower speed than said spindle, a generally cylindrical locating sleeve mounted upon said free end of the sleeve member, a grinding wheel mounted on the projecting end of said spindle and Within said locating sleeve, a pilot shaft fixed to the free end of said locating sleeve and co-axial therewith for engaging in the guide of the valve seat, the axis of the grinding Wheel spindle being ofi-set from the common axis of the locating sleeve and pilot shaft, said locating sleeve having adjacent the free end thereof, an externally frustro-conical portion for engaging in the frustro-conical portion of the valve seat and also having .4 an opening interrupting said frustro-conical portion and extending for less than half the circumference of said frustro-conical portion, and the grinding wheel being positioned within said locating sleeve so as to have a portion of its operative grinding surface projecting through said opening.

4. A tool for grinding an annular valve seat having a frustro-conical portion and an axially aligned guide, said tool comprising an outer body, of generally hollow cylindrical formation, a sleeve member mounted for rotation co-axially within the outer body and having a free end projecting beyond an end of the outer body, a spindle rotatably mounted co-axially within said sleeve member and having one end projecting beyond the said free end of the sleeve member, the said free end of the sleeve member having an external screwthread, a generally cylindrical locating sleeve mounted upon said free end of the sleeve member, said locating sleeve having at one end an internally screwthreaded circular opening which is eccentric in relation to the axis of the locating sleeve and which engages the external screwthread on the free end of the sleeve member, a grinding wheel mounted on the projecting end of said spindle and Within said locating sleeve, a pilot shaft fixed to the free end of said locating sleeve and coaxial therewith for engaging in the guide of the valve seat, said locating sleeve having adjacent thetfree end thereof, an externally frustro-conical portion for engaging in the frustro-conical portion of the valve seat and also having an opening interrupting said frustroconical portion and extending for less than half the circumference of said frustro-conical portion and the grinding wheel being positioned within said locating sleeve so as to have a portion of its operative grinding surface projecting through said opening.

References Cited in the file of this patent UNITED STATES PATENTS 

